A loop portion of a bus wire connected to an electric blasting device is passed through a first magnetic core together with a first loop-like wire, and the first loop-like wire is further passed through a second magnetic core provided in a detonator. The detonator includes a second loop-like wire which is passed through the second magnetic core, an electric bridge connected to the second loop-like wire and a fuse head provided around the electric bridge. When a pulsatory high frequency current is supplied to the bus wire, high frequency currents are induced in the first and second loop-like wires by electromagnetic induction. Then the current flows through the electric bridge of the detonator to fire the primer explosive.